1. Field of the Invention
The present invention relates to multioscillator ring laser gyroscopes and, more particularly, to simplified dispersion equalization field coils therefor.
2. Description of Related Art and Other Considerations
Dispersion field coils in conventional multioscillator ring laser gyroscopes (RLG), such as described in U.S. Pat. No. 4,470,701, are used primarily to counteract undesirable magnetic fields produced by Faraday rotator magnets. Outside magnetic fields can also produce undesirable bias effects if the gyroscope is insufficiently shielded. Such coils are typically laced through holes in the frame of the gyroscope and surround its plasma discharge region. Specifically, the holes are drilled into the frame, which is composed of a glass having a low coefficient of thermal expansion, and the edges of the holes are bevelled or otherwise rounded to avoid damage to the insulation of the wires. The customary coil lacing process is effected manually by threading and winding the coil wires through the holes in the glass frame, and results in high assembly costs.
Mechanization of the above lacing process by use of a special coil winding machine has been investigated, but this option was rejected as adding cost to the gyroscope and placing it at a market disadvantage vis-a-vis competing products.
This existing coil design can also produce undesirable tangential or transverse magnetic fields, which could result in incorrect output readings. The coil windings, as presently installed, are designed to produce a magnetic dispersion field optimally aligned with the gain bore of the gyroscope, but may produce tangential fields at the mirror surfaces. Thus, the fields at the mirrors are not normal to their surfaces and, as a result, this may influence a gyroscope bias known as "transverse Kerr effect."
Further, the above described coil design does not easily allow for changes in the number of turns of wire, for whatever reason. For example, in the manufacture of a lot or number of gyroscopes having the same design, the entire lot needs to have essentially the same dispersion equalization current but, in practice, uniformity in dispersion equalization current does not occur. Therefore, those gyroscopes, which fail to be within tolerance, must be reworked by adding or subtracting turns of wire in their coils. The present design involving laced coils makes such changes in the coils difficult and expensive.